Build your first Ubuntu Core image

[degville]

NOTE TO EDITORS

This page of documentation has moved to:
https://documentation.ubuntu.com/core/tutorials/build-your-first-image

It will continue to be updated and supported only from the new location. We also welcome community contributions.

To suggest improvements, or to notify us of an issue, please use the Give feedback button on the new page. Thank you!

This tutorial will guide you through the steps required to create your own Ubuntu Core image, with your own selection of snaps, and install it on a Raspberry Pi.

The same process can be used to build Ubuntu Core images for various hardware and devices.

Here’s what you’ll need for the tutorial

• a basic understanding of Linux and the command line
• a Raspberry Pi 4 Model B, or later
  • 4GB+ microSD card
  • keyboard and display (for setup only)
  • Ethernet or wireless network connectivity
• host system running Ubuntu 22.04 LTS or later
• 10GB of free storage space
• a microSD card reader
• a wireless network and access to the internet

The above requirements are specific to this tutorial. Other host distributions can be used, and other target platforms are supported.

Step-by-step guide

Here’s an overview of the steps required with links to our separate tutorials that deal with each individual step:

• 1. Create an Ubuntu One account
  • 1. Create the account online
  • 2. Retrieve your developer account id
• 2. Create the model assertion
  • 1. Download a model assertion
  • 2. Edit the model assertion
  • 2.1 authority-id and brand-id
  • 2.2 timestamp
  • 2.3 snaps
  • 2.4 my-model.json
  • 3. A complete model assertion
• 3. Sign the model assertion
  • 1. Create a key
  • 2. Register the key
  • 3. Sign the model
• 4. Build and write the image
  • 1. Compile the image
  • 2. Write the image
• 5. Boot the image
  • 1. Boot Ubuntu Core
  • 1.1 Configure a network connection
  • 2. Connect to the device

[rpjday1]

What’s with the timestamp example in section 4.2 ending in “0Z”? Is this some weird but valid variation?

[degville]

I think it’s the UTC offset from the timestamp in the model. Not sure how that’s been generated, but it’s accepted.

[rpjday1]

I’m not sure this page qualifies as a “Quick Start” guide … it jumps right into creating model assertions and building your own image. A quick start might be just downloading a ready-to-go image and booting your Raspberry Pi, or maybe even downloading a QEMU image and booting that.

[ogra]

That wouldn’t fit very well with the title, would it?

[degville]

I think @rpjday1 is referring to the title in the navigation which is indeed Quickstart guide (for consistency with other docs). But I think he’s right. It’s a tough place to start and not quick. I’ll shuffle this - put the install guides first and then this second with a new name.

[rpjday1]

At the very least, those first two tabs could be reversed … start with “Install Ubuntu Core” after which rename the other tab to “Build your own image”. That would flow more smoothly. Ah, as was just done.

[rpjday1]

I would put, as a first tutorial, downloading and running a QEMU image, so people don’t even need to invest in hardware. I think we have such a tutorial kicking around somewhere, so just add that as a TO-DO item.